{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451001.MRSN","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451001.MRSN","canonicalUrl":"https://icboms.com/littelfuse-inc/0451001.MRSN","factsUrl":"https://icboms.com/api/mcp/products/0451001.MRSN","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 Series, Board Mount (Cartridge Style Excluded) SMD Fuse, 0451001.MRSN, 1 A, 125 V AC/DC, Fast Blow, 2-SMD Square End Block, 50 A Breaking Capacity.","salesMarkdown":"## Active production — 1 A fast-blow SMD fuse for board-level protection The Littelfuse 0451001.MRSN is an active-production NANO²® 451 series surface-mount fuse rated 1 A at 125 V AC and 125 V DC, with a fast-blow response time. It clears faults up to 50 A at rated voltage, which covers most secondary-side protection scenarios in DC power rails and AC control circuits. The 2-SMD square end block package (6.10 mm x 2.69 mm x 2.69 mm) fits standard reflow assembly processes and occupies minimal board area, making it suitable for dense PCB layouts in power distribution, telecom, and industrial control modules. ## Breaking capacity and I²t coordination With a breaking capacity of 50 A at 125 V AC/DC, this fuse safely interrupts fault currents up to that level without rupturing the package — critical for ensuring the downstream PCB trace or component does not see sustained overcurrent. The 0.459 melting I²t value lets you calculate whether the fuse holds during capacitor inrush or motor start transients; a lower I²t means faster opening under surge conditions. ## Thermal range and approvals CSA and UR approval marks confirm acceptance for North American and Canadian equipment listings per UL 248-14 and CSA C22.2 No. 248.14.","metaTitle":"0451001.MRSN Littelfuse NANO² 451 1A 125V Fast-Blow SMD Fuse","metaDescription":"Active Littelfuse 0451001.MRSN NANO² 451 surface-mount fuse, 1A 125V AC/DC, 50A breaking capacity, CSA/UR approved. Available to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Circuit Protection"],"specifications":{"Mfr":"Littelfuse Inc.","Color":"-","Series":"NANO²® 451","Package":"Tape & Reel (TR) Cut Tape (CT)","Fuse Type":"Board Mount (Cartridge Style Excluded)","Melting I²t":"0.459","Mounting Type":"Surface Mount","Response Time":"Fast Blow","Package / Case":"2-SMD, Square End Block","Product Status":"Active","Approval Agency":"CSA, UR","lifecycle_stage":"unknown","Size / Dimension":"0.240\\\" L x 0.106\\\" W x 0.106\\\" H (6.10mm x 2.69mm x 2.69mm)","DC Cold Resistance":"0.153 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"1 A","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$3.1300","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/604a0e4c498aa97d2607992508357d04.pdf","sourceUrl":null},"ai":{"faq":[{"question":"Where can I buy the 0451001.MRSN and check availability?","answer":"The 0451001.MRSN is an active Littelfuse part available through independent distribution."},{"question":"What is the breaking capacity of the 0451001.MRSN?","answer":"The fuse has a breaking capacity of 50 A at its rated 125 V AC or DC — it safely interrupts fault currents up to that level without casing rupture."},{"question":"What approvals does the 0451001.MRSN carry?","answer":"It is approved by CSA (Canadian Standards Association) and UR (Underwriters Laboratories Recognized Component), covering North American equipment safety listings."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451001.MRSN","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451001.MRSN when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:49:49.435Z","lastPublished":"2026-08-11T15:49:49.435Z","indexable":true}}